phy: Track power-on and init counts in uclass

phy: Track power-on and init counts in uclass

On boards using the RK3399 SoC, the USB OHCI and EHCI controllers share
the same PHY device instance. While these controllers are being stopped
they both attempt to power-off and deinitialize it, but trying to
power-off the deinitialized PHY device results in a hang. This usually
happens just before booting an OS, and can be explicitly triggered by
running "usb start; usb stop" in the U-Boot shell.

Implement a uclass-wide counting mechanism for PHY initialization and
power state change requests, so that we don't power-off/deinitialize a
PHY instance until all of its users want it done. The Allwinner A10 USB
PHY driver does this counting in-driver, remove those parts in favour of
this in-uclass implementation.

The sandbox PHY operations test needs some changes since the uclass will
no longer call into the drivers for actions matching its tracked state
(e.g. powering-off a powered-off PHY). Update that test, and add a new
one which simulates multiple users of a single PHY.

The major complication here is that PHY handles aren't deduplicated per
instance, so the obvious idea of putting the counts in the PHY handles
don't immediately work. It seems possible to bind a child udevice per
PHY instance to the PHY provider and deduplicate the handles in each
child's uclass-private areas, like in the CLK framework. An alternative
approach could be to use those bound child udevices themselves as the
PHY handles. Instead, to avoid the architectural changes those would
require, this patch solves things by dynamically allocating a list of
structs (one per instance) in the provider's uclass-private area.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Peter Robinson <pbrobinson@gmail.com> - Rock960